Angle between two lines using direction cosines for JEE

Formula

\(\cos\theta=l_1l_2+m_1m_2+n_1n_2\)

Variables: \((l_1,m_1,n_1)\) and \((l_2,m_2,n_2)\) are direction cosines of the two lines; \(\theta\) is the angle between them.

Conditions: \(0\leq \theta\leq \pi\).

Finding acute/obtuse angle between intersecting lines.